Comment on "Effects of Magnetic Field Gradient on Ion Beam Current in Cylindrical Hall Ion Source

Magnetic Resonance Imaging (MRI) observes tissue water in the presence of a magnetic field gradient to study morphological changes such as tissue volume loss and signal hyperintensities in human disease. These changes are mostly non-specific and do not appear to be correlated with the range of severity of a certain disease. In contrast, Magnetic Resonance Spectroscopy (MRS), which measures many different chemicals and tissue metabolites in the millimolar concentration range in the absence of a magnetic field gradient, has been shown to reveal characteristic metabolite patterns which are often correlated with the severity of a disease. In-vivo MRS studies are performed on widely available MRI scanners without any “sample preparation” or invasive procedures and are therefore widely used in clinical research. Hydrogen (H) MRS and MR Spectroscopic Imaging (MRSI, conceptionally a combination of MRI and MRS) measure N-acetylaspartate (a putative marker of neurons), creatine-containing metabolites (involved in energy processes in the cell), choline-containing metabolites (involved in membrane metabolism and, possibly, inflammatory processes),

Download Full-text

Magnetic hybrid materials interact with biological matrices

Physical Sciences Reviews ◽

10.1515/psr-2019-0114 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Christine Gräfe ◽

Elena K. Müller ◽

Lennart Gresing ◽

Andreas Weidner ◽

Patricia Radon ◽

...

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Hybrid Materials ◽

Biomedical Application ◽

Magnetic Field Gradient ◽

Apical Cell ◽

Cell Type ◽

Cell Layers ◽

Barrier Model

Abstract Magnetic hybrid materials are a promising group of substances. Their interaction with matrices is challenging with regard to the underlying physical and chemical mechanisms. But thinking matrices as biological membranes or even structured cell layers they become interesting with regard to potential biomedical applications. Therefore, we established in vitro blood-organ barrier models to study the interaction and processing of superparamagnetic iron oxide nanoparticles (SPIONs) with these cellular structures in the presence of a magnetic field gradient. A one-cell-type–based blood-brain barrier model was used to investigate the attachment and uptake mechanisms of differentially charged magnetic hybrid materials. Inhibition of clathrin-dependent endocytosis and F-actin depolymerization led to a dramatic reduction of cellular uptake. Furthermore, the subsequent transportation of SPIONs through the barrier and the ability to detect these particles was of interest. Negatively charged SPIONs could be detected behind the barrier as well as in a reporter cell line. These observations could be confirmed with a two-cell-type–based blood-placenta barrier model. While positively charged SPIONs heavily interact with the apical cell layer, neutrally charged SPIONs showed a retarded interaction behavior. Behind the blood-placenta barrier, negatively charged SPIONs could be clearly detected. Finally, the transfer of the in vitro blood-placenta model in a microfluidic biochip allows the integration of shear stress into the system. Even without particle accumulation in a magnetic field gradient, the negatively charged SPIONs were detectable behind the barrier. In conclusion, in vitro blood-organ barrier models allow the broad investigation of magnetic hybrid materials with regard to biocompatibility, cell interaction, and transfer through cell layers on their way to biomedical application.

Download Full-text

Evaluation of Position RMS Error from Magnetic Field Gradient for Surgical EM Tracking Systems

2020 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) ◽

10.1109/i2mtc43012.2020.9128837 ◽

2020 ◽

Cited By ~ 1

Author(s):

Mattia Alessandro Ragolia ◽

Filippo Attivissimo ◽

Attilio Di Nisio ◽

Anna Maria Lucia Lanzolla

Keyword(s):

Magnetic Field ◽

Field Gradient ◽

Magnetic Field Gradient ◽

Tracking Systems ◽

Rms Error

Download Full-text

Alloy surface composition resulting from fabrication, as determined by s.i.m.s. (secondary ion mass spectrometry)

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1980.0092 ◽

1980 ◽

Vol 295 (1413) ◽

pp. 134-135

Keyword(s):

Secondary Ion Mass Spectrometry ◽

Surface Composition ◽

Ion Beam ◽

Sample Surface ◽

Beam Current ◽

Ion Source ◽

Beam Current Density ◽

Dynamic Mode ◽

Static Mode ◽

Subsequent Performance

In s.i.m.s. the sample surface is ion bombarded and the emitted secondary ions are mass analysed. When used in the static mode with very low primary ion beam current densities (10 -11 A/mm 2 ), the technique analyses the outermost atomic layers with the following advantages (Benninghoven 1973, I975): the structural—chemical nature of the surface may be deduced from the masses of the ejected ionized clusters of atoms; detection of hydrogen and its compounds is possible; sensitivity is extremely high (10 -6 monolayer) for a number of elements. Composition profiles are obtained by increasing the primary beam current density (dynamic mode) or by combining the technique in the static mode with ion beam machining with a separate, more powerful ion source. The application of static s.i.m.s. in metallurgy has been explored by analysing a variety of alloy surfaces after fabrication procedures in relation to surface quality and subsequent performance. In a copper—silver eutectic alloy braze it was found that the composition of the solid surface depended markedly on its pretreatment. Generally there was a surface enrichment of copper relative to silver in melting processes while sawing and polishing enriched the surface in silver

Download Full-text